The EPA said yesterday that New Yorkers close to the World Trade Center at the time of the 9/11 attacks, particularly rescue workers, probably were at risk of serious respiratory and other health problems.

In a draft study focusing on the contamination which followed the WTC collapse, the Environmental Protection Agency said Ground Zero had become a toxic and dangerous area after two passenger jets destroyed the Twin Towers.

“Persons exposed to the extremely high levels of ambient particulate matter … during the collapse of the World Trade Center towers and for several hours afterwards were likely to be at risk for immediate acute (and possibly chronic) respiratory and other types (e.g., cardiovascular) of symptoms,” the EPA said.

The agency, which has promised to clean up and test apartments in the area south of Canal Street, said it had not begun to measure some contaminants until three days after the attacks. Other contaminants were not gauged until Sept. 23, so that several potential health impacts “cannot be evaluated with certainty,” the EPA said.

The agency said it had measured “elevated concentrations” of contaminants in and around Ground Zero for one to three months after Sept. 11 and that those levels had not returned to normal until January or February 2002.

The EPA said its draft study was subject to a 60-day review and “comment period” during which independent experts could offer advice and suggest changes.

The agency also released another study yesterday in which scientists exposed mice to particles collected at the World Trade Center site.

Researchers found that samples from the WTC contained a heavy concentration of calcium, a high dose of which could cause mild lung inflammation and air flow obstruction in mice. A similarly high dose in humans could cause short-term respiratory effects such as inflammation and cough, the EPA said.

Dr. William Farland, an EPA research administrator, told the Post that the agency intended to conduct followup tests on rescue personnel who were at the site immediately after the attacks.

“These were the people in the plume,” said Farland. “We need to follow them, because there’s a potential for risk and exposure.”

A report released earlier this week by a team of environmental scientists studying Ground Zero pollution found that the soot in the air of lower Manhattan in the days after 9/11 was less likely to cause cancer and other long term health problems than many had feared.